System for adjusting the inclination of print heads

ABSTRACT

A system for adjusting the angular orientation in a first plane of a plurality of print head cartridges or groups of cartridges arranged adjacent to each other on a carriage which can be reciprocated in a Y-direction, wherein each of said cartridges or group of cartridges is mounted on said carriage to be tiltable in said first vertical plane, wherein for each of said cartridges or groups of cartridges said carriage is provided with first adjustors for adjusting the angular orientation of the respective cartridge or group of cartridges, said system being provided with second adjustors arranged remote from said carriage for adjusting said angular orientation of said cartridge or group of cartridges, said second adjustors selectively, operatively communicating with said first adjustors of a selected one of said cartridges or group of cartridges.

BACKGROUND OF THE INVENTION

[0001] This non-provisional application claims priority under 35 U.S.C.§ 119(a) on Patent Application No. 03075380.0 filed in Europe on Feb. 5,2003, which is herein incorporated by reference.

[0002] 1. Field of the Invention

[0003] The present invention relates to a system for adjusting theangular orientation of print head cartridges arranged on a carriage of aprinter, such as a laser jet printer or an inkjet printer.

[0004] 2. Related Art

[0005] Print head cartridges are usually arranged on a carriage that isreciprocated in the so-called Y-direction over the width of the surfacethat is to be printed. The carriage is provided with means for receivingand holding the cartridge with the print head nozzles directed towardssaid surface. During printing, the surface to be printed, such as apaper web, is moved in the X-direction, which is perpendicular to theY-direction.

[0006] Nowadays high-resolution printing processes require a highaccuracy in the position of the print head nozzles with respect to thepaper. It may therefore be desirable to be able to compensate forpossible misalignment of the print head nozzles with the imaginaryX-lines and/or Y-lines of the input image template or grid to adjust theposition of the print head nozzles in the X- and Y-direction withrespect to the carriage.

[0007] It has been suggested to adjust the position of print headnozzles in the X-direction of one print head of a pair by using acam-lever mechanism arranged on the carriage. A stationary lever arm canbe operated to extend into the path of the cam-lever to rotate thecam-lever about a Z-axis extending perpendicular to the paper. The camon the cam-lever is then urged against the print head cartridge so thatthe cartridge is tilted about an axis parallel to the Y-direction. Thisknown adjusting mechanism with two levers is quite complex and occupiesmuch space, in particular the cam-lever which projects from the carriagein the X-direction. In addition, due to its constructional width, theknown adjusting mechanism cannot properly be arranged on the carriagefor two adjacent print heads. In any event, arranging a plurality ofsuch adjusting mechanisms on carriages carrying a plurality of printheads would increase the weight of the carriage in an unacceptablemanner.

SUMMARY OF THE INVENTION

[0008] The present invention provides an adjusting mechanism for printheads on a carriage of a printer whereby the weight of the carriage isincreased to a limited degree only, even in the case of a plurality ofprint heads.

[0009] The present invention further provides an adjusting mechanism forprint heads on a carriage of a printer that functions with a high degreeof accuracy and with which the position of the print head nozzles in theX-direction can be fine-tuned.

[0010] From one aspect, the present invention provides a system foradjusting the angular orientation in a first plane perpendicular to theX-direction of a plurality of print head cartridges or groups ofcartridges arranged adjacent to each other on a carriage which can bereciprocated in the Y-direction. Each of the cartridges or group ofcartridges is mounted on the carriage to be tiltable in said firstvertical plane, wherein for each of said cartridges or groups ofcartridges, said carriage is provided with a first means for adjustingthe angular orientation of the respective cartridge or group ofcartridges, said system being provided with a second means arrangedremote from said carriage for adjusting the angular orientation of saidcartridge or group of cartridges, said second adjusting means beingarranged to be selectively, operatively coupled with said firstadjusting means of a selected one of said cartridges or group ofcartridges.

[0011] The division of the adjusting mechanism into first adjustingmeans on every cartridge or group of cartridges of a plurality ofcartridges or groups of cartridges on the carriage and second adjustingmeans positioned remote from the carriage and which can be selectivelyoperatively coupled with a selected first adjusting means, makes itpossible to keep the construction of the adjusting means on the carriagesimple and requires only one second adjusting means for all firstadjusting means.

[0012] By selectively coupling the selected first adjusting means andthe second adjusting means, the adjusting means can be operatedpositively and therefore in a controlled manner, permitting afine-tuning of the relative position of the cartridges, in particulartheir nozzles, in the X-direction. In addition, the weight of thecarriage will not be increased to too high a degree.

[0013] In a further development, the second adjustment means arepivotable in a plane perpendicular to the Y-direction between aretracted position and a coupled position, so that the space occupied bythe movement and presence of the second adjustment means may bemaintained within limits. Advantageously, the second adjustment meansmay then be movable towards the coupled position in a direction towardsthe nozzle side of the cartridge. In this way, the path of movement ofthe second adjustment means is maintained within the usual boundaries ofthe printer.

[0014] In a further development, each one of said cartridges or group ofcartridges is provided with said first adjusting means, so that anoptimal adjustability is realised, with only one second adjusting means.

[0015] The second adjusting means can be arranged at one end of the pathof reciprocal movement of said carriage. In an advantageous manner, thesecond adjusting means may then be arranged in a print head cleaningunit, so that the space already occupied by the cleaning unit is usedmore efficiently.

[0016] In a further development, the first adjusting means are adaptedfor tilting said cartridge by being moved in said first plane, so thatthe space occupied in the Y-direction is maintained within limits. Theheads can be placed closer to each other.

[0017] The first adjusting means may then be adapted for tilting saidcartridge by being moved substantially vertically, that is,perpendicular to the paper web to be printed, whereby the space in thehorizontal directions is kept within limits.

[0018] Advantageously, the first adjusting means are adapted for tiltingsaid cartridge by being moved according to a substantially linear path,so that as little space as possible is required.

[0019] In a constructionally simple and reliably operating embodiment,the first adjusting means comprise a first stop surface on saidcartridge and a movable wedge-shaped second stop surface in contacttherewith.

[0020] In a further development, the first and second adjusting meanscomprise first and second cooperating coupling means and means forbringing the first and second coupling means into and out of operativeengagement with each other. Thus, the first adjusting means may comprisea spindle forming a rotational unity with the first coupling means, thefirst and second coupling means having matching unroundedcross-sections. In this way, a quick and reliable coupling can beestablished.

[0021] The process of coupling can be improved when the second couplingmeans forms a male part, and, even more, when the male part is providedwith a pilot surface.

[0022] In a further development the first and second coupling means havehexagonal cross-sections for improving the rotational engagement betweenthe male and female parts.

[0023] Advantageously, the system according to the present inventionfurther comprises means for adjusting the position of the secondadjustment means in the X-direction, so that deviations in position inthe X-direction of the first adjusting means (for instance due to adifferent size of the cartridge or staggered placement of thecartridges) can be compensated for.

[0024] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

[0026]FIG. 1 schematically shows a top view of a printer carriage of aprinter disposed above a paper web;

[0027]FIG. 2 schematically shows a side view of a cartridge adjustmentarrangement according to the present invention;

[0028]FIGS. 3A and 3B are views in perspective of opposite sides of aholder for a cartridge in a system according to the present invention;and

[0029]FIG. 4 is a schematic side view of a system according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In the top view of FIG. 1, a printing station 1 is shown,arranged over and aside of a support 2 for a paper web 5 which is movedin the direction X, which may be a horizontal direction. The printingstation 1 comprises a guide 6 for a carriage 4 on which a plurality ofcartridges or print heads 7 are supported and which is movable in thedirection Y, which may also be horizontal.

[0031] A cleaning station 3 is arranged adjacent to the support 2. Thecleaning station is arranged below the guide extension 6 b, which isaligned with the guide portion 6 a which is positioned over the support2.

[0032] As has been schematically shown in FIG. 4, the cleaning station 3has a cleaning head 50 arranged on top of a vertical bar 51 which ismovable up and down in the direction I by operating means that are notfurther shown.

[0033] All print heads 7 are indirectly supported in frames 30 which arefixedly mounted on the carriage 4 and support sub-frames 40 onto whichthe print heads 7 are mounted. The sub-frames 40 are tiltable in thedirection D about an axis S parallel to the Y direction with respect tothe frames 30.

[0034] This tilting movement is more clearly shown in FIG. 2, where aprint head 7 is schematically depicted in two orientations, namely astandard, vertical orientation, shown in full lines and a tiltedorientation, shown in broken lines. At its lower side, the print head isprovided with a nozzle plate 20 having nozzles which, when activated,discharge ink in the Z-directions.

[0035] The frame 30 supports a linearly, vertical shiftable wedge 12,which has an inclined wedge plane 15 and a threaded hole 13. A top end14 of a spindle 10 is threadedly received in hole 13 and is rotatablyguided in bearings 11 on frame 30, see also FIG. 3B. At the lower end ofthe spindle 10 a hexagonal socket 9 is fixed, in which the upper end ofa hexagonal rod 25 is insertable when displaced upwards in the directionA. This insertion is improved by pilot faces 9 a.

[0036] The sub-frame 40 is provided with a horizontally extending bar 16which is in engagement with wedge face 15.

[0037] As can be seen in FIG. 3A, the sub-frame 40 is accommodated inframe 30 which has two horizontal legs 41 which serve as support for aprint head which is not shown. The sub-frame 40 is provided with 2 stopson extending bar 16 for defining the standard orientation of the printhead. The sub-frame 40 can be tilled around axes S and the sub-frame 40together with the head and moves in the direction D.

[0038] In the cross-section of the cleaning unit 3 shown in FIG. 4, thewalls 3 a-b define a housing 60 in which the cleaning head 50 and theoperative means therefor, as well as an adjusting mechanism for themovement of the hexagonal rod 25 are accommodated. This mechanismincludes a motor 61 accommodated in housing 23 which drives a shaft 62supported in bearings 64 arranged in walls 3 a,b of the housing 60. Whenactivated, the motor 61 rotates the shaft 62 in the directions E, thecams 63 a,b being displaced in the linear directions F. Cam 63 a isconnected to bracket 72 of a sub-frame 71, which bracket is rotatableabout axis T in the directions H. The sub-frame 71 comprises an L-strip73 which is provided with a slot 75 in which a cam 66 mounted on a wheel65 is slidingly received. The wheel 65 is rotatable in the directions Gby a motor which is not shown.

[0039] The sub-frame 71 carries a motor 74 for driving a shaft 26carrying hexagonal rod 25. The shaft 26 is supported on a spring 27 forbiasing the outer end of the rod 25 upwards during engagement of thepilot faces 9 a of the socket 9.

[0040] In or before operation, the print heads 7 may be moved by thecarriage 4 towards the cleaning unit 60. When it has been establishedthat one, some or all of the print heads need to be adjusted in theirorientation in the X-direction, the carriage 4 is driven to position theframe 30 of the print head 7 in question in front of the mechanism 70.Then the motor for the wheel 65 is activated, so that the cam 66 movesand thus the slot 75 and consequently the sub-frame 73 is rotatedupwards in the direction H about axis T so that the upper end of rod 25moves upwards (A) and operatively and matingly engages socket 9 on theframe 30 in question. Then motor 74 is activated so as to rotate rod 25and therewith spindle 10 in the direction B. As a result, the upper end14 will rotate within threaded hole 14, whereby the wedge 12 will moveupwards or downwards in the direction C. Consequently, the bar 16 willbe urged sidewards away from the frame 30 or under the influence ofbiasing means arranged between the frames 30 and 40 but not shown moveback to the desired extent.

[0041] By way of example, and referring to FIG. 2, the sub-frame 40 andtherewith the print head 7 can be tilted in the direction D aboutfulcrum S so that the nozzles 21 change their orientation from, by wayof example, a vertical discharging orientation to a more slantingorientation. This results in an X-displacement of the ejected inkdots onthe receiving medium 5. The desired degree of rotation is determined bycontrol means which are not shown and which operate the adjustingmechanism in response to measurements on the printing results.

[0042] When the adjustment operation for one print head has beencompleted, the same operation can be repeated for another one of theprint heads, if so desired.

[0043] In case the print heads are replaced by print heads of differentdimensions, the location of the rod 25 may be adapted by activatingmotor 61 to move the bracket 72 in the direction F to a position inwhich the path of movement of the upper end of rod 25 will coincide withsocket 9.

What is claimed is:
 1. A system for adjusting the angular orientation ina first plane of a plurality of print head cartridges or groups ofcartridges arranged adjacent to each other on a carriage which can bereciprocated in a Y-direction, wherein each of said cartridges or groupsof cartridges is mounted on said carriage to be tiltable in a firstvertical plane perpendicular on the Y-direction, wherein for each ofsaid cartridges or groups of cartridges said carriage is provided withfirst adjustors for adjusting the angular orientation of the respectivecartridge or groups of cartridges, said system being provided withsecond adjustors arranged remote from said carriage for adjusting saidangular orientation of said cartridge or groups of cartridges, saidsecond adjustors selectively, operatively communications with said firstadjustors of a selected one of said cartridges or groups of cartridges.2. The system according to claim 1, wherein the second adjustors arepivotable in a plane perpendicular to the Y-direction between aretracted position and a coupled position.
 3. The system according toclaim 2, wherein the second adjustors are movable towards the coupledposition in a direction towards the nozzle side of the cartridge.
 4. Thesystem according to claim 1, wherein each one of said cartridges orgroups of cartridges is provided with said first adjustors.
 5. Thesystem according to claim 1, wherein said second adjustors are arrangedat one end of the path of reciprocal movement of said carriage.
 6. Thesystem according to claim 5, wherein said second adjustors are arrangedin a print head cleaning unit.
 7. The system according to claim 1,wherein said first adjustors are adapted for tilting said cartridge bybeing moved in said first vertical plane.
 8. The system according toclaim 7, wherein said first adjustors are adapted for tilting saidcartridge by being moved substantially vertically, that is perpendicularto the paper web to be printed.
 9. The system according to claim 1,wherein said first adjustors are adapted for tilting said cartridge bybeing moved in a substantially linear path.
 10. The system according toclaim 7, wherein said first adjustors comprise a first stop surface onsaid cartridge and a movable wedge-shaped second stop surface in contacttherewith.
 11. The system according to claim 1, wherein said first andsaid second adjustors comprise first and second cooperating couplingmeans and means for bringing the first and second coupling means intoand out of operative engagement with each other.
 12. The systemaccording to claim 11, wherein said first adjustors comprise a spindleforming a rotational unity with said first coupling means, said firstand said second coupling means having matching, not roundedcross-sections.
 13. The system according to claim 11, wherein the secondcoupling means form a male part.
 14. The system according to claim 13,wherein the male part is provided with a pilot surface.
 15. The systemaccording to claim 12, wherein said first and second coupling means havehexagonal cross-sections.
 16. The system according to claim 12, whereinsaid second coupling means are rotatable.
 17. The system according toclaim 1, further comprising means for adjusting the position of saidsecond adjustors in the Y-direction.